1. Field of the Invention
The present invention relates to a device used in the machining of a workpiece. More particularly, the present invention relates to a device that aids the positioning and placement of a drill or tap in drilling and tapping holes in a workpiece, including a workpiece having a nonplanar sidewall through which a hole or tap is to bored.
2. Discussion of the Prior Art
Guides have long been used in the art of drilling and tapping holes in a workpiece. Generally, a prior art guide includes a body having a plurality of guide holes of varying diameters. In use, the guide hole having the desired diameter is positioned by hand over the place on the workpiece where the hole is to be drilled or the tap made. A user then holds the guide in place with one hand while drilling the hole using a hand powered drill with the other hand.
Once such prior art guide is depicted in U.S. Pat. No. 4,589,806 to Rotta, Jr. (the '806 patent). The '806 patent discloses a guide having a body including four radial arms having guide holes at the distal ends thereof. The guide holes are of varying diameters, increasing the utility of the device.
The guide device of the '806 patent, however, is relatively wide as compared with the diameters of the guide holes, reducing the ability to position the guide device on a relatively narrow workpiece surface. The relatively large distance between the guide holes also renders the device generally difficult to position on a nonplanar surface, such as the sidewall of a cylinder. For example, when used for positioning a drill on the sidewall of a cylinder, once the appropriate guide hole is selected and positioned over the desired location on the sidewall for a drill hole or tap, much of the guide device hangs off to the side of the sidewall hole location. This may result in the guide rocking so that the guide hole is not perpendicular to the sidewall location, possibly causing the bore to be angled through the sidewall, rather than being perpendicular. In addition, the relatively small area of the guide that is in contact with the sidewall of the workpiece may result in slippage of the guide during the forming of the hole or tap possibly causing the hole to be formed in the wrong location.
U.S. Pat. No. 5,415,502 to Dahlin (the '502 patent) discloses a guide device having a generally cylindrical body with a plurality of guide holes formed through the periphery thereof. The guide holes are shown having varying diameters. As with the device shown in the '805 patent, the device of the '502 patent is relatively wide when compared to the diameter of the guide holes, resulting in the difficulties associated with boring holes in relatively narrow workplaces and on nonplanar surfaces discussed in more detail above.
There exists in the art a need to provide a drill and tap guide having a shape permitting use with drilling and tapping into workpieces of varying sizes and shapes. In addition, there exists a need for a guide having structure that assists in ensuring that a hole or tap is bored perpendicular to the surface of the workpiece adjacent to the hole or tap. Placement of the tap in alignment is important to prevent breaking the tap, a particular problem in the art of placing and using taps.